JP2782135B2 - Vehicle travel guidance device - Google Patents

Description

DETAILED DESCRIPTION OF THE INVENTION

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a vehicle travel guide system for searching for a route from a starting point set on a road map displayed on a screen to a destination and guiding the vehicle. .

[0002]

2. Description of the Related Art Recently, a starting point and a destination are arbitrarily set on a road map displayed on a screen, and an optimum route from the set starting point to the destination is set based on digital map data. A vehicle travel guide device has been developed which searches for a vehicle and guides the vehicle along the searched route (for example, Japanese Patent Laid-Open No. 62-133).
No. 600 or JP-A-1-173297).

As digital map data, the actual road shape as shown in FIG. 3 is approximated by broken lines as shown in FIG. It consists of data on the connection status between the two.

Conventionally, as a method of performing a route search based on digital map data, for example, Dijkstra
The connected nodes on the digital map are tracked one after another so that the required distance is minimized according to a known algorithm such as a method, and a search for a route that minimizes the distance from the starting point to the destination is performed. The cost of a line segment from the point of departure to the destination (eg, distance, average travel time or a combination thereof, or a combination of road attributes such as distance, average travel time and road width, tolls, etc.)
There are various route search methods for minimizing.

[0005] At this time, a plurality of candidate routes are searched while giving a rank to the route search according to the degree of the cost of the line segment from the starting point to the destination, and one of them is arbitrarily selected. It is conceivable to do so.

However, in this case, if the user does not want to select the first searched route as shown in FIG. When a route that minimizes the cost of the line segment up to the ground O is searched, a route that partially bypasses the previously searched route by a small distance is searched as shown in FIG. In some cases, there is no point in switching the search route to another one and selecting it.

[0007] When one of the search routes from the starting point to the destination is switched to another while being selected as the optimum route due to traffic conditions or the like, another route different from the previously searched route is used. Searching for a route and presenting the route is meaningful for guiding the vehicle to travel.

[0008]

The problem to be solved is that, based on the digital map data, the cost of the line segment from the starting point set on the road map to the destination is determined. When sequentially searching for a plurality of candidate routes while giving a ranking to the route search, the route to be searched next becomes almost the same as the previous search route, and another route different from the previous search route is not searched. Is to put it.

[0009]

SUMMARY OF THE INVENTION The present invention is based on digital map data so that an optimal route from a starting point to a destination can be selected according to traffic conditions and the like. When sequentially searching for a plurality of routes with an order according to the cost of the line segment up to the ground, a different route different from the previous search route is searched first so as to be searched next. After performing processing to increase apparently the cost of the line segment in the searched route, means for searching for a route that minimizes the cost of the line segment is taken next.

[0010]

FIG. 1 shows an example of the configuration of a vehicle traveling guide device according to the present invention.
And a direction sensor 2 that outputs a signal proportional to the amount of direction change accompanying the traveling of the vehicle, for example, detects a change in the angular velocity in the yaw direction, and counts the number of pulse signals from the distance sensor 1 to measure the traveling distance of the vehicle. At the same time, the current position on the XY coordinate for each constant traveling distance of the vehicle is obtained by successively calculating the change in the traveling direction according to the output signal of the direction sensor 2, and A signal processing device 3 comprising a microcomputer for performing control and data of a current position of a position on the X-Y coordinates, which is constantly changing, obtained by the signal processing device 3 are sequentially stored, and finite continuous position information of the vehicle is stored. A travel locus storage device 4 for storing and holding the same, and a map information storage medium in which road map information based on digital map data is stored in advance. 5, a storage medium reproducing device 6 for selectively reading road map information of a necessary area from the storage medium 5, and a predetermined road map based on the read road map information. A display device 7 for updating and displaying the current position of the vehicle on the road map projected on the display along with the traveling locus and the traveling direction of the vehicle at the current position as necessary as the vehicle travels; and a signal processing device. 3, an operation command is given to the display device 7, a selection of a map to be displayed on the display device 7 and a setting of a starting point and a destination of the vehicle on the displayed map are performed. To change the direction of the displayed map and running trajectory,
An operation device 8 is provided which can appropriately change the display mode, such as shifting the display position, partially enlarging the map and the traveling locus, and selecting the display scale.

[0011] In the above configuration, the selectively read road map is displayed on the screen of the display device 7 and the signal processing is performed in accordance with the traveling of the vehicle from the starting point set on the map. The current position on the XY coordinates is calculated by the device 3 in accordance with a preset scale of the map, and the calculation result is sequentially transmitted to the travel locus storage device 4 to update the stored content. At the same time, the stored contents are read out and sent to the display device 7.

As a result, for example, the display device 7 shown in FIG.
As shown in the figure, on the map displayed on the screen, a display mark M1 indicating the current position of the vehicle, a display mark M2 indicating the traveling direction of the vehicle at the current position, and a traveling locus from the starting point S to the current position. The display mark M3 is simulated and displayed following the running state of the vehicle.

The present invention relates to such a vehicle travel guide device, wherein the signal processing device 3 sets the departure set on the road map displayed on the screen based on the digital map data read from the map information storage medium 5. A route search that minimizes the cost of a line segment from a point to a destination (eg, distance, average travel time, or a combination thereof) is performed, and an optimal route that takes into account traffic conditions such as one-way traffic is determined. Then, for example, the optimal route on the road map displayed on the screen is indicated by a special color, and the vehicle can be guided so that the current position of the vehicle is updated and displayed on the optimal route. Like that.

Here, various known methods are widely applied to the basic algorithm of the route search and the determination of the optimum route itself.

In such a case, in particular, in the present invention, under the control of the signal processing device 3, when the searched route is inappropriate due to traffic conditions or the like due to an input operation by the operation device 8, The search route can be canceled.

If the searched route is canceled, the signal processing device 3 then minimizes the cost of the line segment from the starting point set on the road map to the destination. Search for a route.

At this time, as shown in FIG. 7, the cost of the line segment on the previously searched route A is apparently determined so that another route B different from the previously canceled route A is searched next. A process for increasing the size is performed so that a route almost similar to the route A searched earlier is not searched.

The specific processing is executed, for example, as follows.

Now, the total number of line segments 1 from the starting point set on the road map to the destination is N = {1, 2, 3,
, N}, and a set of the line segments l is {l _i | _i = [1,
n]}.

The route P from the starting point to the destination is represented by the following equation (1).

[0021]

(Equation 1)

Here, the path P is represented by the following equation (2).

[0023]

(Equation 2)

If the cost of the line segment l _pi (here, attention is paid only to the distance) is C _pi , the distance L between the starting point and the destination is given by the following equation (3).

[0025]

(Equation 3)

Now, it is assumed that a route P that minimizes the cost (distance) of the line segment from the starting point to the destination has been searched.

When the searched route P is canceled, each line segment l constituting the canceled route P
_{P1, l P2, l P3,} ... for, substituted its cost _{C P1, C P2, C P3} , ... , and as shown in the following equation _{(4), C P1 ',} C P2', C P3 ', the ... I do.

[0028]

(Equation 4)

Here, x is a weight coefficient, x ≧ 1.0, and y is a weight, y ≧ 0.0. In particular,
Set x = about 1.2 and y = 0.0.

The cost C of each line segment l _P1 , l _P2 , l _P3 ,...
_After replacing _{P 1} , C _P2 , C _P3 ,... And searching again for a route P ′ that minimizes the cost (distance) of the line segment from the starting point to the destination, the search is performed first. Has been replaced so that the cost of the line segment on the route P is apparently large, the line segment is excluded as much as possible,
A different route P 'different from the previous route P is searched.

By repeating the above operation,
The third, fourth, and fourth ranks are ranked according to the cost of the segment.
Are sequentially searched.

For example, if the roads on the map are sparse, the cost of the line segment on the first route is 1.2 times (x
= 1.2) and the route search is performed again, the cost is still smaller than the cost of the line segment in the second route,
In such a case, x = 1.5 to 2.x may be selected.
It is better to set to about 0.

Further, for example, when roads on a map such as an urban area are dense, there are many alternative roads, and it is necessary to consider that a partially common route may be searched again. It is better to set x to about 1.1 to 1.3.

However, the weighting factor x and the weighting y may be variable in some cases.

[0035]

As described above, in the vehicle travel guide device according to the present invention, the cost of the line segment from the starting point set on the road map to the destination based on the digital map data is minimized. When a plurality of routes are sequentially searched in order according to the degree of the line segment, a process of apparently increasing the cost of the line segment in the previously searched route is performed, and then the cost of the line segment is reduced. The search for the smallest route is performed, so when canceling a route that was previously searched due to traffic conditions, it is possible to search for a different route from the previous search route, This has the advantage that the optimum route from the starting point to the destination can be arbitrarily selected according to circumstances or the like.

[Brief description of the drawings]

FIG. 1 is a block diagram showing an embodiment of a vehicle travel guide device according to the present invention.

FIG. 2 is a diagram showing an example of display contents in the embodiment.

FIG. 3 is a diagram illustrating an example of an actual road shape.

FIG. 4 is a diagram showing a digital map of the road in FIG. 3;

FIG. 5 is a diagram illustrating an example of a previously searched route;

FIG. 6 is a diagram illustrating an example of a route that partially bypasses a previously searched route by a minute distance;

FIG. 7 is a diagram illustrating an example of a next search route different from the previous search route.

[Explanation of symbols]

 DESCRIPTION OF SYMBOLS 1 Distance sensor 2 Direction sensor 3 Signal processing device 4 Travel locus storage device 5 Map information storage medium 6 Storage medium reproduction device 7 Display device 8 Operation device

Claims (5)

(57) [Claims] 1. A departure set on a road map displayed on a screen, based on digital map data comprising data on nodes of connection points and end points of each line when an actual road shape is approximated by a line. In a vehicle travel guidance device that performs a route search that minimizes the cost of a line segment from a point to a destination and guides the vehicle, the apparent cost of the line segment on the previously searched route After performing the process of increasing the size, the next step is to search for the route that minimizes the cost of the line segment, and the route is searched in the order according to the degree of the cost of the line segment from the starting point to the destination. A vehicle travel guidance device, wherein one of the routes is selected. 2. The vehicle travel guide device according to claim 1, wherein the cost of the line segment is a distance. 3. The vehicle travel guide device according to claim 1, wherein the cost of the line segment is an average required time. 4. The vehicle travel guide device according to claim 1, wherein the cost of the line segment is a combination of the distance and the average travel time. 5. The vehicle travel guidance device according to claim 1, wherein the cost of the line segment is a combination of road attributes such as a distance, an average travel time and a road width, and a toll.